Imagine trying to put two giant pieces of Lego together when they're both travelling at 1000 mph!
That's what it was like for Chinese astronauts on Sunday when their spacecraft docked with another module in space.
Normally dockings like this use an auto-pilot.
But the team, which included China's first female astronaut, did this one manually.
The Shenzhou-9 spacecraft docked with the Tiangong-1 lab module as part of plans for China to have its own space station.
The country hopes to have it built by 2020.
"It was a precise and perfect docking," said Wu Ping from China's manned space programme.